Noise reducing means for electrical apparatus



NOISE REDUCING MEANS FOR ELECTRICAL APPARATUS Filed Sept. 12, 1963 July 12, 1966 T. R. SPECHT ETAL 5 Sheets-Sheet 2 July 12, 1966 T. R. SPECHT ETAL 3,260,974

NOISE REDUCING MEANS FOR ELECTRICAL APPARATUS 5 Sheets-Sheet 5 Filed Sept. 12, 1963 United States Patent NOISE REDUCING MEANS FOR APPARATUS Theodore R. Specht, Sharon, Pa., and Gwyn N. Crump,

Hartford Township, Ohio, assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 12, 1963, Ser. No. 308,409 Claims. (Cl. 336--90) This invention relates in general to electrical apparatus and more particularly to means for reducing the noise radiated by electrical apparatus.

Consideration of the sound that is radiated by elec trical apparatus, and the effect of this sound on the residents in the vicinity, is a factor in the choice of electrical apparatus which must be used in or near population centers. To avoid complaints, it is often necessary to reduce the noise radiated by the electrical apparatus. Some of the means used to reduce sound radiation taught by the prior art are heavy walls located around the electrical apparatus, spring mounting of the electrical apparatus, and sound absorbing material placed around or inside the electrical apparatus. These methods of reducing sound radiation have disadvantages because heavy walls are expensive and take up much space, spring mounting of electrical apparatus makes the electrical apparatus'diflicult to ship without damage and sound absorbing materials are usually not effective at all sound frequencies.

Accordingly, it is the general object of this invention to provide a new and improved electrical apparatus.

It is a more particular object of this invention to provide a new and improved electrical apparatus which radiates a minimum of noise.

Briefly, the present invention accomplishes the above cited objects by providing an electrical apparatus which is closely coupled to a massive pad. The electrical apparatus is surrounded by a barrier which is coupled at one end to the massive pad. The other end of the barrier is attached to the top of the electrical apparatus. The barrier may have a single wall ora plurality of walls. If the barrier has a plurality of walls, the space between walls may be filled with oil or any suitable sound absorbing material.

Further objects and advantages of the invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the invention, reference may be had to the accompanying drawings in which:

FIG. 1 is an elevation of an electrical inductive apparatus embodying the teachings of our invention;

FIG. 2 is a transverse sectional view of an embodiment of our invention applied to an electrical transformer;

FIG.3 is a vertical sectional view of a second embodiment of our invention;

FIG. 4 is a vertical transverse sectional view of athird embodiment of our invention; and

FIG. 5 is a view partly in elevation and partly in section of an embodiment of our invention employing remote coolers.

In FIG. 1 one may see an external view of an embodiment of our invention. An electrical inductive apparatus is closely coupled to a concrete pad 14 by a nonresilient material such as asphalt-felt 16. An access door 20 is provided in the outer wall 12 of the electrical inductive apparatus for purposes of maintenance and inspection. Windows 18 are provided in the outer wall 12 to permit direct viewing of interior electrical gauges and controls through the outer wall 12 of electrical apparatus.

ELECTRICAL ice bushings 24 by conductors such as conductor 50. The,

tank 28 is provided with a cover 38 and a bottom 29. Intermediate the cover 38 and the bottom 29 is located a panel or enclosure 40. The enclosure 40 may be provided with braces such as braces 42 and may be coated with a vibration dampening compound 44. An air space 45 is provided between the panel 40 and the tank 28.

Sound absorbing material such as glass fiber batts 31 may be provided in'this air space. The bottom 29 of the transformer tank is coupled to a massive concrete pad 46 by providing a non-resilient material 48 between the transformer bottom 29 and the massive concrete pad 46. We have found that either asphalt-felt or ordinary putty are good materials to rigidly couple the transformer bottom to the concrete pad.

In operation, the magnetic core 34 vibrates chiefly due to the well-known magnetic phenomenon of magnetostriction. The audible vibrations of the magnetic core 34 are transmitted through an insulating and cooling fluid 36 to the tank 28. The cover 38 will also vibrate somewhat due to sound transmitted from the cooling fluid through the air space 25. The distance from the cover 38 to the core 34 attenuates the vibrations that reach the cover 38. Also, the air space 25 acts as a cushion to vibration-s; hence, the vibrations of the cover 38 are much less in magnitude than the vibrations of the walls of the tank 28. The audible noise produced by vibrations of the cover 38 is ordinarily not objectionable because most of the noise so produced is radiated upward where it is dissipated in the atmosphere. The bottom 29 of the tank 28 also tends to vibrate because of the pulsations being transmitted through the cooling fluid 36 by the vibrating magnetic core 34. However, the bottom 29 of the tank 28 is prevented from vibrating due to its intimate contact with the massive concrete pad 46 through the coupling material 48. We have attached the outer panel 40 between the bottom 29 of the tank 28 and the cover 38 of the tank 28 because these two points are points of low vibration. The panel 40 is further separated from the tank 28 by the air space 45. Audible noise produced by the tank 28 traveling in a horizontal directiton is greatly attenuated by the time it has penetrated panel 40.

Referring to FIGURE 3 of the drawings there is illustrated a transformer 52 constructed according to another embodiment of our invention, which is similar to the transformer shown in FIG. 2 in that it is provided with a magnetic core 68, a coil assembly 70, bushings 72, electrical connections such as 74 and a tank 54 partially filled with a liquid coolant 66. The tank 54 is provided with an air space 55 and a top 56. The top 56 of the tank 54 is large enough to extend beyond the tank walls. An oil-tight bottom 58 is provided for tank 54. The bottom 58 also extends beyond the walls of the tank 54. As in the previously described embodiment of our invention, we couple the bottom 58 of the tank 54 to a massive concrete pad 84 by means of a non-resilient material 82. In the instant embodiment of the invention we provide a double walled barrier 62 intermediate the bottom 58 and the top 56 of the tank 54. We connect the doubled walled barrier. 62 with the tank 54 by means of flexible tubes or pipes such as 78 and 80. The flexibility of'the tubes such as 78 and 80 prevents acoustic driving of the barrier 62 by the tank 54. The cooling fluid 66 may now fill the barrier 62 to the same level as the height of the coolant in tank 54-. We have spaced the barrier 62 away from the tank 54 to provide an air space 63. Sound absorbing material such as glass fiber batt 182 may be provided in this air space. The external surface of barrier 62 provides cooling area in contact with the ambient air for cooling the fluid 66 as it becomes heated by the magnetic core 68 and the coil assembly 70. The air space 55 will in great measure attenuate the vibrations being transmitted through the cooling fluid 66 before such vibrations reach the cover 56. The bottom 58 of the tank 54 is prevented from vibrating by its intimate contact with the massive concrete slab 84. We have attached the doubled walled barrier 62 between the top 56 and the bottom 58 of the tank because these are points of minimum vibration. The mass of the cooling liquid 66 in the barrier 62 also exhibits a dampening action on vibrations from the tank 54 that travel in a horizontal direction.

Referring to FIG. 4 of the drawings there is illustrated a transformer constructed according to another embodiment of our invention, in which a hollow outer wall or noise barrier 186 is filled with a solid material 188 such as slag or sand. As in the other embodiments of the invention, the problem is to minimize the noise coming from a transformer tank 86. The transformer tank 86 is provided with braces 108 and and sound absorbing material such as glass fiber batt 184. In the transformer tank 86 is disposed a magnetic core 94 and an electrical coil assembly 92 connected to bushings 98 by conductors such as 96. The transformer tank 86 contains a liquid coolant and electrical insulator such as transformer oil 162. A void space 164 is provided between the transformer oil 162 and an extended top 88 of the transformer tank 86. An extended bottom 98 is provided on the transformer tank 86. By extended top and bottom it is to be understood that the top and bottom extend beyond the tank walls. The noise barrier 186 is located intermediate the extremities of the extended top 88 and the extended bottom 90. A void space 187 is provided between the transformer tank 86 and the sound barrier 106. The transformer bottom 98 is prevented from vibrating by coupling it to a massive concrete pad by means of a bed of non-resilient material such as putty 112.

A series of tests were made on a tank containing a single-phase magnetic core. The core weighed about 4500 pounds and was energized at 60 cycles per second. The magnetic induction was 17,700 gauss. Typical tests are shown in Table I; oil was used inside the barrier of test 5. Tests 9, 7 and 5 show a reduction of the sound level from the bare tank of test 8.

Referring to FIG. 5 of the drawings there is illustrated a transformer and cooling assembly 111 constructed according to still another embodiment of our invention, using remote transformer coolers. Assembly 111 includes a transformer 170 having a tank 172, magnetic core 124, a coil assembly 128, and bushings 132 connected to the coil assembly 128 by conductors such as conductor 130, is provided with an extended top 114 and an extended bottom 116. The walls of the transformer tank 172 are braced with channel members 136. The magnetic core 124 is braced by channel members 126 which are attached to the transformer bottom 116. The transformer tank 172 is filled with a cooling and insulating liquid 134 except for a void space 174 which is provided at the top 114 of the transformer tank 172 to attenuate sound vibrations before they reach the cover 114 and to allow for thermal expansion of the cooling liquid 134. As in the other embodiments of our invention, a sound reduction barrier 118 is provided about the transformer 170. The sound reduction barrier 118 may be coated on at least one side with vibration dampening compound 122; the sound reduction barrier 118 may be braced with braces such as brace for additional rigidity. A void space 119 is provided between the transformer tank 172 and the noise reduction barrier 118. We couple the bottom 116 of the transformer tank 172 to a massive concrete pad 156 by means of a felt pad 158 located sub-adjacent to the transformer bottom 116.

We cool this embodiment of our invention with remotely located radiators or coolers such as radiators 148 and 142. The radiators and their connections are identical hence only radiator 142 will be considered in detail. Radiator 142 is provided with an upper manifold 144 and a lower manifold 146 which are connected by cooling tubes 145. A flexible tube 154 is provided between the upper part of the transformer tank 172 and the sound reduction barrier 118. A flexible tube 152 is provided between the lower part of the transformer tank 172 and the sound reduction barrier 118. These flexible tubes are connected to the upper and lower radiator manifolds 14-4 and 146 by means of flexible, oil-tight connections or couplings 148 and 150. It will be understood that the arrangement shown is adapted for circulation of coolant by natural convection. If greater cooling capacity is required, the cooling liquid 134 may be forced through the cooler 142 by means of a pump or impeller (not shown). The flexible devices such as 152, 154, 148 and 150 prevent transmission of noise from the transformer tank 172 to the barrier 118. The flexible connections 148 and 150 also allow some relative movement between the radiator 142 and the transformer 178. The cooler 142 may be mounted by means of support 168 on the same massive concrete pad v156 as the transformer 170. Alternatively, the cooler 142 may be supported on a separate concrete pad (not shown).

In operation, transformer 170 produces noise when the magnetic core 124 is energized by the coil assembly 128. The bottom of the sound reduction barrier 118 is attached to the substantially non-vibrating extended bottom 116 of the tank 172. The top of the noise reduction barrier 118 is attached to the extended cover 114 of the transformer 178. The vibrations of the transformer tank 172 due to the noise generated by the transformer core 124 and transformer coils 128 will not be directly transmitted to the sound reduction barrier 118 because of the air space 119 and attachment of the sound reduction barrier 118 to points of low vibration. Because the sound reduction barrier 1 18 vibrates with less intensity than the walls of the transformer tank 172, the noise emanting from this embodiment 1111 of our invention in horizontal planes will be greatly attenuated, as shown in Table I. If desired, sound reduction material such as glass fiber batts 138 may be located in the void space 119. Although the batts are shown attached to the wall of the transformer tank 172, the batts may also be attached to the inside of sound reduction barrier 118, or the batts may be freely suspended in the void space 119 so as not to impede heat transfer from the transformer 170.

It will, therefore, be apparent that there has been disclosed an enclosure for electrical inductive apparatus which greatly reduces noise transmitted from the electrical apparatus.

Since numerous changes may be made in the abovedescribed apparatus and different embodiments may be made without departing from the spirit thereof, it is intended that all the matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

'1. Electrical inductive apparatus comprising a sealed tank having sidewall, top and bottom portions, a magnetic core and electrical winding assembly disposed in said tank, a liquid coolant disposed in said tank, the top and bottom portions of said tank extending outwardly from the sidewall portions for a predetermined distance, barrier means having a plurality of spaced wall members disposed to surround the sidewall portions of said tank in predetermined spaced relation, the wall members of said barrier means being connected to the extended top and bottom portions of said tank, said barrier means forming a hollow a-ir chamber between said barrier means and said tank for reducing the sound energy radiated by the electrical inductive apparatus.

2. The electrical inductive apparatus of claim \1 including solid sound dampening means disposed between the plurality of spaced wall members of said barrier means.

3. The electrical inductive apparatus of claim 1 ineluding liquid means disposed between the plurality of spaced wall members of said barrier means.

4. The electrical inductive apparatus of claim 3 wherein the liquid means in said barrier means is the same as the liquid coolant disposed in said tank, and including conduit means connecting the liquid in said tank with the liquid in the spaced wall members of said barrier means.

5. The electrical inductive apparatus of claim 1 including base means and non-resilient means, the bottom of said tank being coupled to said base means through said non-resilient means, to substantially reduce the magnitude of tank vibrations which are transmitted to said base means.

References Cited by the Examiner UNITED STATES PATENTS 1,030,091 9/1912 Johnson 336-99 X 1,232,834 7/1917 Nichols 336-58 X 1,601,307 9/ 1926 Hill 336-99 X 1,846,887 2/1932 Matthews 336-100 1,872,245 8/1932 Clark 336-58 X 2,731,606 1/1956 Stewart et a1. 336-100 X 2,734,096 2/1956 Ennis 336-100 X 3,077,946 2/ 1963 Wilkins 336-100 X 3,102,246 8/1963 Hony 336-100 X 3,175,173 3/1965 Welch 336-100 X ROBERT K. SCI-IAE'FER, Primary Examiner. JOHN F. BURNS, Examiner.

T. J. KOZMA, Assistant Examiner. 

1. ELECTRICAL INDUCTIVE APPARATUS COMPRISING A SEALED TANK HAVING SIDEWALL, TOP AND BOTTOM PORTIONS, A MAGNETIC CORE AND ELECTRICAL WINDING ASSEMBLY DISPOSED IN SAID TANK, A LIQUID COOLANT DISPOSED IN SAID TANK, THE TOP AND BOTTOM PORTIONS OF SAID TANK EXTENDING OUTWARDLY FORM THE SIDEWALL PORTIONS FOR A PREDETERMINED DISTANCE, BARRIER MEANS HAVING A PLURALITY OF SPACED WALL MEMBERS DISPOSED TO SURROUND THE SIDEWALL PORTIONS OF SAID TANK IN PREDETERMINED SPACED RELATION, THE WALL MEMBERS OF SAID BARRIER MEANS BEING CONNECTED TO THE EXTENDED TOP AND BOTTOM PORTIONS OF SAID TANK, SAID BARRIER MEANS FORMING A HOLLOW AIR CHAMBER BETWEEN SAID BARRIER MEANS AND SAID TANK FOR REDUCING THE SOUND ENERGY RADIATED BY THE ELECTRICAL INDUCTIVE APPARATUS. 